Transforming growth factor beta (TGFβ) regulates normal cell processes such as proliferation, differentiation and apoptosis as well as the invasiveness and metastatic spread of cancer cells. The TGF Beta family includes Transforming Growth Factor Beta 1, 2, and 3 (TGF-β1, TGF-β2, and TGF-β3) which are highly pleiotropic cytokines that virtually all cell types secrete. TGF-β molecules act as cellular switches that regulate processes such as immune function, proliferation, and epithelial-mesenchymal transition. TGF-β1 plays an important role in controlling the immune system. TGF-β1 is released by some T cells—regulatory T cells (Tregs)—to inhibit the actions of other T cells. TGF-β1 prevents the activation of quiescent helper T cells and cytotoxic T cells and can inhibit the secretion and activity of cytokines such as IFN-γ, IL-2 and TNF-α (Wahl S et al (1988) J Immunol 140(9):3026-3032; Tiemessen M et al (2003) Int Immunol 15(12):1495-1504; Wahl S et al (2006) Immunol Rev 213:213-227).
TGFβ in Cancer
TGF-β is both a tumor suppressor and a tumor promoter. Indeed, loss or attenuation of TGF-β signaling in epithelial cells and stroma is permissive for epithelial cell transformation (Siegel, P. M. and Massague, J. (2003) Nat Rev Cancer 3:807-820; Bierie, B. and Moses, H. L. (2006) Nat Rev Cancer 6:506-520). On the other hand, introduction of dominant-negative TGF-β receptors into metastatic cancer cells has been shown to inhibit epithelial-to-mesenchymal transdifferentiation, motility, invasiveness, and survival, supporting the tumor promoter role in TGF-β in fully transformed cells (reviewed Dumont, N. and Arteaga, C. L. (2003) Cancer Cell 3:531-536). In addition, excess production and/or activation of TGF-β by cancer cells can contribute to tumor progression by mechanisms involving modulation of the tumor microenvironment (Siegel, P. M. and Massague, J. (2003) Nat Rev Cancer 3:807-820; Wakefield, L. M., and Roberts, A. B. (2002) Curr Opin Genet Dev 12:22-29; Arteaga, C. L. (2006) Curr Opin Genet Dev 16:30-37). These data have provided a rationale in favor of blockade of autocrine/paracrine TGF-β signaling in human cancers with a therapeutic intent. Some tumors resistant to conventional anticancer chemotherapy overexpress TGF-βs (Lui, P et al (2000) Int J Oncol 16:599-610; Teicher, B. A. et al (1997) In Vivo 11:453-461), and inhibitors of TGF-β have been shown to reverse this resistance (Teicher, B. A. et al (1997) In Vivo 11:463-472). In addition, overexpression of TGF-β ligands have been reported in most cancers, and high levels of these in tumor tissues and/or serum are associated with early metastatic recurrences and/or poor patient outcome (Wojtowicz-Praga, S. (2003) Invest New Drugs 21:21-32; Ito, N., et al. (1995) Cancer Lett 89:45-48; Shariat, S. F., et al (2001) Cancer 92:2985-2992; Shariat, S. F., et al (2001) J Clin Oncol 19:2856-2864; Tsushima, H., et al (2001) Clin Cancer Res 7:1258-1262; Rich, J. N. (2003) Front Biosci 8:e245-e260). Animal studies with pan-TGF-β antibody have shown inhibition of tumor recurrence or metastasis in fibrosarcoma, colon cancer, and breast cancer (Terabe M et al (2003) J Exp Med 198:1741-1752; Nam J-S et al (2008) Cancer Res 68(10):3835-3843), and reduced radiation-induced acceleration of metastatic breast cancer (Biswas S et al (2007) 117:1305-1313). It is notable that in radiation studies, thoracic radiation and chemotherapy in metastatic breast cancer models specifically induced plasma TGF-β1 levels (Biswas S et al (2007) 117:1305-1313).
TGF-β and Immunomodulation
Successful treatment of immunotherapy against cancer depends on inducing an integrated and durable immune response to cancer antigens. Evidence indicates that this may be achieved by overcoming the immunosuprressive milieu in the tumor microenvironment attributed to TGFβ-mediated immune suppression. For example, TGFβ suppresses both innate and the adaptive arms of the immune response. Regarding the innate immune response, TGFβ modulates NK cells cytolytic activity. Furthermore, TGFβ also inhibits DC maturation and cytokine production, thereby promoting a tolerogenic environment. In addition, TGFβ produced by tolerogenic DC contributes to Treg cell differentiation. TGFβ can also favor the differentiation of macrophage lineage, an M2 cell, that produces high levels of TGFβ. M2 macrophage competes with DC for antigen but does not present them. Regarding the adaptive immune response, TGFβ mitigates the function of effector CD8 and CD4 T cells by inhibiting T helper and CTL activity and promoting apoptosis of effector T cells. It has been shown that overproduction of TGF-β by tumor cells and Gr1+CD11b+ myeloid derived suppressor cells leads to evasion of host immune surveillance and tumor progression (Yang L et al (2010) J Bone Miner Res 25(8):1701-1706). Membrane associated TGF-β1 contributes to blockade of activation of memory T-cells that exist in an anergic state within the tumor microenvironment (Broderick L. et al Banket R B (2006) J Immunol 177:3082-3088.) TGF-mediated inhibition of CTL functions during antitumor immunity through several mechanisms. For example, TGFβ directly inhibits CTL function by suppressing the expression of several cytolytic genes, including the genes encoding granzyme A, granzyme B, IFNG and FAS ligand. TGFβ also attenuates the effector function of antigen-specific memory CD8 T cells and blocks TCR signaling of tumor infiltrating lymphocytes and alters cytokine production in CD8 T cells (Ahmadzadeh, M. & Rosenberg, S. A. (2005) J. Immunol. 174:5215-5223, di Bari, M. G. et al. (2009) Cancer Immunol Immunother 58:1809-1818).
In addition to turning off the immune response, TGFβ promotes the differentiation of regulatory T cells (Tregs) and recruites their migration to the tumor site. In human cancers, accumulating data shows that CD4+FOXP3+ Tregs are present in tumor local sites. Sato et al has demonstrated that the ratio of CD8+ T cells to CD4+CD25+FOXP3+ Tregs is an important prognostic indicator, with a low ratio associated with a poor outcome in ovarian cancer patients, indicating the essential role of Treg in protective anti-tumor immune responses (Sato, E et al (2005) PNAS 102(51):18538-18543). Considering the importance of Treg in suppression of anti-tumor immune responses, controlling Tregs is an important and clinically relevant goal. TGFbeta induces development of Treg cells. Since Tregs suppress antitumor immunity, a decreased in the percentage of Tregs in peripheral blood and at the tumor site is evaluated as a biomarker for effective immune therapy.
Blockade of TGFβ signaling leads to the enhancement of NK- and CTL-mediated antitumor activity (Arteaga C L et al (1993) J Clin Invest 92:2569-76; Bollard C M et al (2002) Blood 99:1379-87). In studies in mice, it has been shown that adoptive transfer of tumor-reactive, TGF-β-insensitive CD8+ T cells, rendered insensitive by retroviral mediated gene therapy with a dominant negative TGF-β receptor, into immunocompetent mice was able to eradicate lung metastasis of mouse prostate cancer (Zhang Q, et al (2005) Cancer Res 65:1761-9; Zhang, Q et al (2006) Mol Cancer Ther 5:1733-1743). Generic blockade of TGF-β response in mice inhibited prostate cancer metastasis, but led to widespread inflammatory disease in the animals (Shah A H, et al (2002) J Immunol 169:3485-91).
Targeting TGFβ with Neutralizing Antibodies to Enhance Cancer Immunotherapy
Evidence of TGFβ production by tumor cells and by myeloid-derived suppressor cells (MDSC) present at the tumor site along with TGFβ immune suppressive activity at the tumor site strongly supports that blocking TGFβ can enhance antigen uptake, presentation, and activation of antitumor immune response mediated by therapeutic vaccines. Indeed, recent studies have demonstrated that blockade of TGF-β, using mouse TGF-β generic antibody 1D11 (which recognizes TGF-β1, TGF-β2 and TGF-β3), synergistically enhances tumor vaccines in animal models via CD8+ T cells (Terabe M et al (2009) Clin Cancer Res 15:6560-6569; Takaku S et al (2010) Int J Cancer 126(7):1666). Evaluating immunological indicators such as an activation of effector T-cells within the tumor compartment in patients receiving these therapies can serve as biomarkers or biosignature for monitoring immune-mediated killing of tumor cells and response to therapy.
TGFβ isoforms (β1, β2, and β3) are involved in many biological processes, therefore, antibodies that bind all three isoforms of TGFβ may potentiate autoimmune toxicity. To minimize toxicity, antibody that binds specifically to TGFβ1 may be better tolerated. Treatment of cancer or other TGFβ-mediated disorders may be improved by use of a neutralization antibody that only binds to TGFβ-1.
Accordingly, it would be desirable to develop TGFβ-1 specific antibodies, particularly antibodies which can be utilized in mouse animal models and which demonstrate increased efficacy and applicability in diagnosis and therapy, and it is toward the achievement of that objective that the present invention is directed.
The citation of references herein shall not be construed as an admission that such is prior art to the present invention.